With the development of electrical devices, such as cell phones and tables have become thin and light for convenient carrying. So optical lens mounted in electrical devices is needed to have small focal length and small effective diameter of light exiting surface.
Further, people hope that modern electrical devices can capture more scenery and have high image quality while taking photos in a low light environment. So, optical lens with wide angles are used to acquire more visible light to capture more images, and optical lens with large aperture are used to improve the image quality when taking photos in low light environment. Thus, the optical lens applied in the electrical device not only need to have small length and small effective diameter of exiting surface, but also need to have wide view angle and large aperture.